Field
The present disclosure relates to network management. More specifically, the present disclosure relates to a method and system for efficiently balancing multicast traffic over virtual link aggregations (VLAGs).
Related Art
The exponential growth of the Internet has made it a popular delivery medium for multimedia applications, such as video on demand and television. Such applications have brought with them an increasing demand for bandwidth. As a result, equipment vendors race to build larger and faster switches with versatile capabilities, such as multicasting, to move more traffic efficiently. However, the size of a switch cannot grow infinitely. It is limited by physical space, power consumption, and design complexity, to name a few factors. Furthermore, switches with higher capability are usually more complex and expensive. More importantly, because an overly large and complex system often does not provide economy of scale, simply increasing the size and capability of a switch may prove economically unviable due to the increased per-port cost.
As more time-critical applications are being implemented in data communication networks, high-availability operation is becoming progressively more important as a value proposition for network architects. It is often desirable to aggregate links to multiple switches to operate as a single logical link (referred to as a virtual link aggregation or a multi-chassis trunk) to facilitate load balancing among the multiple switches while providing redundancy to ensure that a device failure or link failure would not affect the data flow. A switch participating in a virtual link aggregation can be referred to as a partner switch of the virtual link aggregation.
Currently, such virtual link aggregations in a network have not been able to take advantage of the multicast functionalities available in a typical switch. Individual switches in a network are equipped to manage multicast traffic but are constrained while operating in conjunction with each other as partner switches of a virtual link aggregation. Consequently, an end device coupled to multiple partner switches via a virtual link aggregation typically exchanges all the multicast data with only one of the links (referred to as a primary link) in the virtual link aggregation. Even when the traffic is for different multicast groups, that multicast traffic to/from the end device only uses the primary link. As a result, multicast traffic to/from the end device becomes bottlenecked at the primary link and fails to utilize the bandwidth offered by the other links in the virtual link aggregation.
While virtual link aggregation brings many desirable features to networks, some issues remain unsolved in multicast traffic forwarding.